Uni-Protractor Set tonearm alignment


Looks like Dertonarm has put his money where his mouth is and designed the ultimate universal alignment tractor.

Early days, It would be great to hear from someone who has used it and compared to Mint, Feikert etc.

Given its high price, it will need to justify its superiority against all others. It does look in another league compared to those other alignemt devices

http://www.audiogon.com/cgi-bin/cls.pl?anlgtnrm&1303145487&/Uni-Protractor-Set-tonearm-ali
downunder
John,
Thank you for taking my comments with good humor and responding politely. I took your original comments as just another shot at Dertonarm. While we are all full of ourselves sometimes (and full of sh-t other times) - myself not the least guilty - I have not found a huge amount of fault in D's intellectual approach to things. I have found more fault in the intellectual rigor, or lack thereof, of those who have attacked him in this thread (and others).

1) As to his comment on Baerwald IEC being a '9" standard', I read a different meaning into his comment - I thought it was a throwaway - a comment on fact rather than a normative statement. I will re-read it.
2) As to his reasons for recommending that one alignment (and keep in mind, it is, as far as I know, only for one particular tonearm), he has stated in this thread and others that for his longer (i.e. lower value inner groove radius) records, which are classical and have crescendos/climaxes near the end of the record, given his priorities it makes sense to have the lowest tracking distortion in the second half. I don't disagree on that point. Tracking distortion is, unfortunately, usually calculated assuming a constant velocity of signal (10cm/sec at 1000Hz for mono as per DIN 45537 (1962) and 8cm/sec for stereophonic some 20yrs later). Crescendos have a wide variety of frequencies, including timpani and bass drums, which are far lower than 1000Hz and this may therefore increase peak velocity load on the cantilever/stylus/cart motor in the inner grooves, making the practical use of a constant peak velocity across the record less relevant. If this were a universal truth about music and its placement on the record, it might behoove someone to come up with some 'new math' (neither Baerwald nor Lofgren's equations are set up to be able to accept that kind of 'new' assumption without some serious re-jiggering) to help Baerwald/Lofgren 'weight' the tracking distortion differently, and therefore come up with both different null points. But it is not, and there are enough people who are religious about Baerwald being "best" without thinking about details like this that it is a lost cause.

It is my understanding that Darkling Dert has also said something about your third point (i.e. there is D% more distortion because of factors X, Y, & Z). It is (and I paraphrase here, and I may have misunderstood) that the relative pressures on a cantilever/etc are more violent in the 60mm radius area because the groove modulations are a greater percentage of the radius than they are at 140mm. This I am still thinking about. There is a Japanese guy who has done a whole bunch of research into the finer nuances of the physics of grooves, tonearms, angles, and distortions, but I am still working my way through his stuff. I am sure I don't understand the physics here. At first glance, I would have said a constant 1000Hz signal of amplitude X across the whole record will have the same relative movement on outer groove as inner groove as far as the cantilever is concerned (when moving against the effective mass/inertia of the cart/arm), but given different relative velocity of the stylus through the groove, it may not be the case. I guess it is also possible that stylus aspect change with respect to the groove wall could affect tracking distortion dynamically, but I'm working on that - and in any case, in any practical sense, it still goes back to the earlier point about records and priorities.

3) My point here was that we all get the importance of being as exact as possible in all parameters. It is mathematically so. We can therefore stipulate it. None of us are perfect, but we all try. My comment about the RP1 parameters being inexact was simply me being pedantic and small-minded given the emphasis on exactitude of all parameters. I cannot get 230/17/23.5 on DIN (or 58/146) as shown in the manual to match 63.6/119.5 (also shown in the manual). Something has to give. Your point about 'just adjust angle and mounting distance as necessary' is EXACTLY right and appropriate given the imperfections we each bring to the table when we mount a tonearm/cart, but that is the art, not the science (and most of the critiques of Dertonarm's ideas and protractor on this thread are on the science, not the art, of tonearm setup, and his product I would think is specifically addressing ease of getting the art right - because the science is gotten right by anyone who gets the algebra right).
4) I am not sure that people should need to post their resume of qualifications before coming up with a protractor and marketing it. As you pointed out, the math has been known for decades.
Your first post here implicitly claimed an expertise that you did not pre-qualify, and I did not know who you were without digging, but you so kindly gave your name in your moniker so I went on the internet (which is, as you note, a wonderful thing) and linked your name to a tonearm, which I had heard of and seen before.

In any case, if one has to have a long and public record of producing a good product and supporting it well before one can sell one's product, then nothing would ever get done. How does anyone ever get a first product sold?

I must apologize for the bit about the gold and diamonds. Indeed it was something of a cheap shot, but likewise, you didn't know Dertonarm either. But your implication was that a 10-euro digital caliper and a regular two-point protractor would get the job done just as well for less money. I may end up disagreeing (mine has not arrived yet) after I use it (especially given that I have a few different arms at hand now) but implied in your complaint was that his object was too much money, or an unnecessary expense.

And perhaps Diamante Dert will indeed be able to come up with a Bling-Tractor® (but I, for one, won't be buying it).

I am, however, still noodling on some of the aspects of the SME issue as you brought them up. Without having drawn it out yet, my feeling is that when you change mounting distance because of shorter MH2S than assumed, you have also minutely changed required cartridge mounting angle (because your change in mounting distance is happening on a different vector, and you are therefore changing EL of the physical item (which in my very limited noodling so far, makes me think it should require a (very slightly) different offset angle). I don't know enough about SME tonearms' implicit assumptions to disagree with anyone on what the designers intended, and in any case, my experience so far is that most tonearms have enough play in the mounting parameters that one can be minutely flexible if one wants, even if the design is not meant to accommodate 'play.'
Dear T_bone, just a short side-kick regarding the SME V.....
The offset angle of the headshell is pre-determined - sorry, not my idea, but the idea of the SME-deisgner(s). Given the fact that the mounting hole in the SME V is not really intended to allow anything like a "cartridge offset angle" (which in tonearm geometry not really exists at all - other as by wishful thinking), one can assume that it's designer did so by good reason.
As this mounting hole is (to the regret of many of it's owners past and present - including me ..) not really an elongated one either, the effective length is - at least in theory and designer's intention - pre-determined as well.
Setting the "cartridge offset angle" other than the offset angle of the tonearm's headshell does produce an additional break-down torque in the tonearm's static model - i.e. an additional force vector.
This is a plain mechanical fact - thanks to Isaac N. ...;-) ....
That additional break-down torque does of course influence the skating force.
Now is the SME V designed and constructed strictly following Löfgren A IEC (Baerwald)?
According to it's designer's it is.
According to it's technical parameters it is too.
Can one adapt the SME V to different alignments by moving its slide carriage? It was not intended to adapt to different alignments, but to different position of stylus relative to the mounting hole of the SME V.
The moving of the SME carriage does alter P2S and adapt's the effective length to different distances - in cartridges - between the mounting hole and the stylus.
Thus being able to retain the original Löfgren A IEC alignment is was calculated to.
Best,
D.
Thuchan,
I didn't say you, personally, accepted everything Dertonarm said. I was making a general point.
I am always willing to discuss things, and admit when I'm wrong, the operative words being "discuss" and " wrong".

you said
The (analogue) world is like it is, some good developers and failed ones.
Mostly the failing guys do have a motivation to define the world and tell the succesful developers what they seem to have done in a wrong way.

believe me, I do know producers of tonearms and even turntables who do understand the theoretical implications of proper alignment but they do not really care about it.

Success or failure in hifi and good and bad developers do not necessarily correlate. Making money from a product doesn't mean it is good, merely that a lot of people buy it, and vice versa.

My, and many other's, experience is that often a good product can fail because someone who can influence the market decides it should fail - it's all part of the way markets work... probably best to stay out of it (or, vice versa, as given by your example above,...!)

J
Dertonarm

Glad to see you have responded to my post (via T Bone). Why did you do that? I am willing to discuss the SME issue directly.

You said
Given the fact that the mounting hole in the SME V is not really intended to allow anything like a "cartridge offset angle" (which in tonearm geometry not really exists at all - other as by wishful thinking)...

please read my post to Peter re the conflation of headshell and offset angles and why this is confusing.I am assuming you mean cartridge mounting.

...one can assume that it's designer did so by good reason...
That is a fair assumption, but only if you give a fair analysis of why they might have done it that way.
...As this mounting hole is (to the regret of many of it's owners past and present - including me ..) not really an elongated one either...
Patently not, given it has no slots. Why would this be?

...the effective length is - at least in theory and designer's intention - pre-determined as well...
No. The alignment chosen, ie Baerwald/LofgrenA IEC, is predetermined. The effective length is nominal.

...Setting the "cartridge offset angle" other than the offset angle of the tonearm's headshell does produce an additional break-down torque in the tonearm's static model - i.e. an additional force vector.
This is a plain mechanical fact - thanks to Isaac N. ...;-) ....
This is vague. What do you mean by "break down torque" and why would it be additional if the overhang remains the same? The stylus merely rotates, the groove tangent remains the same, therefore the vector towards the centre remains the same. The only change could be due to the stylus, which may or may not increase the force along the groove tangent depending on the stylus profile.

(re Issac Newton - I have heard he had a great hifi, but maybe Einstein's was better on the super fast transients... (just a joke))

That additional break-down torque does of course influence the skating force.
In what way, by how much?

Now you get to the point:
Now is the SME V designed and constructed strictly following Löfgren A IEC (Baerwald)?
According to it's designer's it is.
According to it's technical parameters it is too.
Can one adapt the SME V to different alignments by moving its slide carriage? It was not intended to adapt to different alignments, but to different position of stylus relative to the mounting hole of the SME V.
Granted, though Lofgren B IEC is much easier than with a slotted headshell - no need to loosen the cartridge, just slide the base.

...The moving of the SME carriage does alter P2S and adapt's the effective length to different distances - in cartridges - between the mounting hole and the stylus.
Correct

Thus being able to retain the original Löfgren A IEC alignment is was calculated to.

Thank you for agreeing.
But why not just say you were wrong, or had expressed yourself badly, previously?

As Piet Hein, the Danish scientist/philosopher/poet said:
The road to wisdom?
Well, it's plain
And simple to express:
Err
And err
And err again
But less
And less
And less.